The objective of the proposed study is the development of immobilized carboxypeptidase G1 (CPG1) systems for use in cancer therapy. Hollow fiber cartridges containing the enzyme in the macroporous shell of the fibers will be prepared. The folate depleting potential and the concomitant antitumor activity of such fibers in experimental animals will be investigated. If successful, this system offers the advantage over conventional intravenous therapy with CPG1 as being less expensive and potentially not immunogenic. Use of the CPG1 hollow fibers to rapidly decrease methotrexate blood levels will also be studied. Pellicular immobilized CPG1 will be employed to remove folates and methotrexate from serum samples.